Latchable spring returned push-toactuate and pull-to-remove switch means



May 3, 1966 w M s, J ET AL 3,249,705

LATCHABLE SPRING RETURNED PUSH-TO-ACTUATE AND PULL-TO-REMOVE SWITCH MEANS Filed July 29, 1963 4 Sheets-Sheet l INVENTORS w. Arms; JR.

JAMES MAI/RICE .D. Fl/llER BY A TTORNE KS May 3, 1966 J. w. AMIS, JR.., ET AL 3,249,705

LATCHABLE SPRING RETURNED PUSHTO-ACTUATE AND PULL-TO--REMOVE SWITCH MEANS Filed July 29, 1963 4 Sheets-Sheet 2 INVENTORS. JAMES w. AM BY MAM/c5 1:. Fl/[LER wz-m May 3, 1966 J. w. AMIS, JR. ET AL 3,249,705

LATCHABLE SPRING RETURNED PUSH-TO-ACTUATE 7 AND PULL-TO-REMOVE SWITCH MEANS Fil ed July 29, 1963 4 Sheets-Sheet B INVENTORS JAfi/Es M Alf/8, JP.

BY fill/RICE D. FULLER ATTORNEYS J. w. AMIS, JR.. ETAI- 3,249,705 LATCHABLE SPRING vRETURIUEID PUSH-TO-ACTUATE AND PULL-TO-REMOVE SWITCH MEANS May 3, 1966 4 Sheets-Sheet 4 Filed July 29, 1963 I J I INVENTORS JAMES M AHIS; JR.

ATTORNEYS Filed July 29, 1963, Ser. No. 298,048

13 Qlaims. (Cl. 200-) This invention relates to improvements in mechanical switching devices and more particularly to switch operating mechanisms of the panel-mounted type such as that covered in copending application Serial No. 197,479 filed May 24, 1962, now Patent No. 3,197,598 issued July 27, 1965, entitled Self Locking Push Button Switch Operating Device. The invention is herein illustratively described by reference to its application to panel-mounted switch operating mechanisms of a preferred type; however, it will be recognized that certain modifications and changes therein and certain other applications thereof may be employed without departing from the essential features comprising the inventive subject matter.

Certain features of the present invention are addressed to specific problems concerning multi-unit switch assemblies of the panel-mounted type. It is desired in such installations to provide accessibility for reclamping individual push button cap assemblies without disturbing other units or dismantling the composite switch assembly, and in fact without necessitating use of tools or performance of any operations behind the mounting panel. As disclosed in said copending application, the cap assemblies are directly removable simply by pulling them out against the yieldable holding force of a detent mechanism. An object of this invention is to provide improvements which permit use of an abruptly acting push button return spring in each switch unit without danger of accidentally disengaging the detent holding the cap assembly in its normal deactuated position. is to provide a practicable, reliable and simple means effective to absorb kinetic energy of the cap assembly on its return motion such that its momentum will not overcome the detent and accidentally release the cap assembly from its mounted position in the panel system.

A further object hereof is to improve the means by which individual push button units of an array of such units are latched in actuated position and by which the actuation of one unit requires and, in fact, causes the tripping of the latch means holding another unit in actuated position. A related object is to provide in such a switch system an improved coordinating means which may be mounted in compact physical association with the abovementioned latch mechanism as a lockout device precluding simultaneous actuation of a plurality of push button units.

The invention is further directed in part to mechanical improvements by which to achieve more reliably responsive coordinative action of interrelated switch-operating units in a composite array than heretofore. In this connection the invention is directed to providing an improved trip-action mechanism, abruptly acting return spring mechanism and related shock absorbing means, so constituted and arranged as to minimize danger'of parts sticking due to any mechanical imperfections or the effects of shock or vibration occurring during switch operation.

A further object hereof is to provide improvements of A specific object hereof, therefore;

nited States Patent 0 3,249,705 Patented May 3, 1966 Ice occupy a minimum area on' the supporting panel, all without adding unduly to the depth of the assembly measured perpendicular to the panel.

A further object is to devise switch operating mechanisms having the features and advantages mentioned which are readily accessible for servicing, which are durable, reliable and trouble-free in operation and which are virtually insensitive to the efliects of shock and vibration both during static and dynamic or operating conditions of individual units. 7

Still another object is to devise improvements of the character described which lend themselves well to unitization of sections of the total switch assembly, including secthe nature described involving relatively few and simple 7 tions of the operating mechanisms, and to making up arand in the number of rows comprised in the array.

In its endeavor to simplify, compact, reduce cost, improve physical proportioning, provide accessibility and improve in other respects switch operating mechanisms of the general nature described, the invention makes multiple use of basic components. Ease of accessibility to parts and subassemblies, and convenience of assembly and disassembly, are still other objectives.

In its preferred embodiment as herein disclosed certain features of the invention reside in the switch operating mechanism including, in each operating unit, a reciprocable plunger and an associated return spring encircling the plunger in captive relationship between first and second stop collars likewise encircling the plunger, with all three elements being movable lengthwise of the plunger and independently of each other. The first and second stop collars are captively retained between first and second stop elements on the plunger and are alternatively engageable with the respective stop elements to which they individually relate in operating on the actuation and return strokes of the plunger. In addition, first and second stop abutments fixed in thehousing or base of the push button unit at respective locations spaced lengthwise of the plunger are also respectively engageable by the first and second stop collars in the operation of the mechanism through its total cycle of actuation and return of the plunger. Thus, on the actuation stroke, during which the plunger is advanced to the hold-down position (i.e. for actuating an associated electrical switch) the first stop element on the plunger carries the first stop collar against one end of the return spring to compress the spring against the second stop collar seated on the second-mentioned stop element. On the return stroke, initiated by triggered release of associated latch mechanism, potential energy stored in the return spring drives the plunger reversely through reaction of, the return spring against the first stop collar and the first stop element engaged thereby. When the first stop collar is arrested in its motion by contact with the first stop abutment in the base or housing structure, continued return motion of the plunger causes its second stop element to pick up the second step collar. The latter thereby initiates recompression of the return spring reacting now against the first stop collar seated on the first stop abutment. This arrests the return motion of the plunger assembly in a relatively gradual manner through absorption of the kinetic energy in the spring. Finally, the plunger is placed at rest in a given position by residual reaction force of the spring positioning the plunger with reference to the stop abutments. By absorbing kinetic energy :of the spring-impelled plunger through recompression of the return spring as described, return motion of the plunger is arrested short of the point to which it might otherwise be carried by its momentum for accidentally tripping the displacement-sensitive detent which holds the push button cap assembly, including the plunger and its associated components, in its housing or receptacle unit.

As a further feature, the plungers of similar switch operating units mounted in the same row have portions which project through individual apertures in an elongated latch plate disposed in a plane perpendicular to the row of plungers and guided for reciprocation in its plane opposite plunger latching position and plunger releasing position. A latch control spring urges the latch plate toward the former position, and a latch-tripping carn enlargement on each plunger is capable of moving it oppositely against the latch control spring by plunger actuation, in order thereby to release any other plunger from latched position. The leading end of the latch-tripping cam enlargement actuates the latch plate to the release position and permits the enlargement to pass through the aperture in the latch plate. The lagging end of the same enlargement, upon having passed through such aperture, now serves as a stop element which seats aga nst the adjacent face of the latch plate, returned to latching position by the latch control spring in the interim, to hold the plunger in latched position, until such tune as it 18 released by actuation of a different plunger. Preferably, the same stop element on the plunger which serves in cooperation with the latch plate also serves as the stop element cooperating with the second stop collar in the spring-return shock absorption mechanism. I

Further, the tapered leading end of the latch-tripping cam enlargement of each plunger, aforementioned, after passing through the associated aperture in the latch plate enters a space formed between complementally formed notches on adjacent ends of lockout plates which are guided for reciprocation in the panel structure in a plane parallel to the latch plate and which are moved away from each other by entry of the cam enlargementinto the space between them. In so doing, these lockout plates are pressed against or into close proximity with ad acent plungers in such relative positions that the opposite ends of the plates interfere with, and prevent actuation movement of, the cam enlargements of the other plungers, until the first plunger is released by separate actuation of either of the other two plungers. Consequently, two plungers may not be actuated simultaneously and the actuation of either plunger releases any other actuated plunger from the latch.

These and other features, objects and advantages of the invention will become more fully evident from the following description thereof by reference to the accompanying drawings.

FIGURE 1 is an isometric view, from a rear aspect showing a switch assembly comprising a row of three operating units arranged in a common structure, the view showing one switch by broken lines in the installed position and showing certain portions of the mechanism in disassembled relationship for clarity of illustration.

FIGURE 2 is an exploded isometric view of principal parts of an individual push button cap assembly.

FIGURE 3 is an exploded isometric view of principal parts of the three-unit housing structure, including the latch and lockout plate members and related guides, and representative fittings designed to carry detachable switch units.

FIGURE 4 is a face view of the two lockout plates cooperating with the three plungers of the illustrated assembly.

FIGURE 5 is a sectional side view with parts broken away showing portions of two of the three switch operating units and their relationship with the latching plate and lockout plates in one operating condition.

FIGURE 6 isa view sirnilar to FIGURE 5 in a different operating condition (viz. in FIGURE 5 the plunger of the unit at the right is in the latched or actuated position, whereas in FIGURE 6 both plungers are at rest in their return position).

FIGURE 7 is a diagrammatic side view illustrating by the positioning of each of the three operating units, the three operating positions of the plungers in the total cycle through which any one unit may operate (viz. the unit at the right is at rest in the return position, the middle unit is at rest in the actuated or latched position, and the unit at the left is in the transistory position in which its return spring is being recompressed in the process of absorbing shock on the return stroke).

FIGURE 8 is a detail view illustrating the preferred detent mechanism in its relationship to other components in the push button cap assembly, including the plunger, with the detent elements retracted in a position permitting Withdrawal of the assembly from its housing.

FIGURE 9 is a fragmentary sectional side view specifically illustrating the shock absorption action of the return spring with overtravel of the plunger on the return stroke limited substantially to the maximum point permitted short of releasing the displacement-sensitive detent mechanism as previously described.

Referring now to the drawings, the particular three-unit package illustrated in the assembly and composite views includes a mounting plate or panel 10 which is adapted to be fastened to a stationary structure such as an instrument panel or the like and is provided with a central opening surrounded by inwardly directed flanges 10a forminga holder for the three integrally joined receptacle units 12, 14 and 16. These units cooperate with the base panel 10 to form part of the supporting structure for the associated three switches S (only one being shown by dotted lines in FIGURE 1) and for the associated three switch-operating push button cap assemblies 18 insertable into the respective receptacle units. As illustrated, the endrnost receptacle units 12 and 16 are of hollow tubular form, rectangular or square in cross section, and composed of channel shaped sections 12a and 16a, respectively, having longitudinal edges 12b and 16b of dovetail configuration matched to the complemental form of the edges of mating channel shaped sections and 160, respectively. The latter sections are joined back-to-back with similar sections which together comprise the wall of the intermediate receptacle unit 14. On the front side of the base panel 10 (i.e. shielded from view in FIGURE 1) the locating elements 20a of edging bars 20 are held by friction in complemental (resilient-wall) retaining sockets 20b carried by the base panel and projecting forwardly from such face thereof. Thus the base panel 10 may be mounted against the back side of an instrument panel, with the receptacle units 12, 14 and 16 and sockets 20b opening forwardly through an aperture in the instrument panel (not shown) so as to permit insertion and removal of edging bars 20 and push button cap assemblies 18 directly from the front side of the panel.

Conventional fittings 22 carried on a rear mounting plate 24 at the inner end of the receptacle assembly support the individual switch units S in detachable manner n positions of alignment with and for operation by the individual push button cap assemblies 18 to be described. Coplanar lockout plates 26 and 28 are retained in face-t0- face sliding contact with the smooth forward surface of the plate 24 and in face-to-face sliding contact with the rear face of the latch plate 30. The latter is slidably retamed in the longitudinal groove 32a formed in the apertured plate 32 extending across the rear end of the recentacle assembly l2, l4 and 16. Groove 32a has a deepening recess 32b at one end to accommodate a latch control spring 34 fitted over a nub 30a on the adjacent end of the latch plate in order to urge such plate endw-ise against a stop pin 320 at the opposite end of plate 32. In so doing, the spring reacts against the inner face of one of two corner brackets 36 held by screws 38 over the ends of the mutually superimposed plates 24 and 32. Screws 40 secure the plates to the receptacle assembly in the absence of corner brackets 36 and in so doing, maintain the spacer plate 42 in position sandwiched between the base plate 32 and the end wall plate 44 common to the inner ends of the three receptacle units 12, 14 and 16. Stop pins 46 near opposite ends of the groove 32a limit the distance either lockout plate 26 or 28 may move in the groove 32a in the direction away from the other lockout plate, so as to maintain these plates in approximately correct position during the process of assembling the total device. Further details and the functioning of the latch mechanism and lockout mechanism will be described hereinafter.

While various details of the push button cap assembly 18 shown in the present application drawings follow the corresponding details of the similar assembly disclosed in the above-cited copendin g application, some reference to them will be made herein for purposes of self-sufficiency of the present disclosure. As shown particularly in FIG- URES 1, 2, 8 and 9, for example, the assembly 1-8 comprises a lamp housing consisting of a base portion 50 and adjoining wall portion 52 with apertures 50a and 5% formed in the base portion. These apertures permit insertion of the filament globes of electric lamps 54 into the interior of the wall structure 52 in order to illuminate the translucent front panel 56a of the push button cap 56, so as to reveal any legend thereon and indicate which of the push buttons is in the actuated position at a given time.

. Rivets 58 and complemental collars 60 hold the lamp receptacle portions together, with the common lamp terminal contact fitting 62 in position to be engaged by the lamp base cont-act rings. The lamp contact buttons 54a come into engagement with electric terminals (not shown) appropriately positioned in the bases of the receptacle units 12, 14 or 16 when the push button assemblies 18 are inserted therein.

Guide tubes 64 are retained in the complementally formed cavities 50c and 52c in the mutually adjacent faces of the lamp housing base and wall portions 50 and 52. The guide tubes are thus aligned transversely t0 the longitudinal axis A of the push button assembly. Detent sliders 66 have enlarged cam follower heads 66a slidably engaged within these guide tubes 64. The slider shafts are encircled by return springs 68 received in the respective tubes for pressing the respective follower elements 66a against opposite sides of the push button plunger 70. The latter is formed in two parts 70' and 76 for convenience of construction, the part 70 being longitudinallybored and threaded to receive the threaded end of the part 70", and the part 70 itself having a threaded end by which it is connected to a section of plunger (70d) secured to the push button cap 56.

As shown best perhaps in FIGURE 8, the plunger 70 has a certain surface configuration over the portion thereof slidably contacted by the detent elements 66a for purposes of controlling the position of these detent elements. In this particular figure (FIGURE 8) the detent elements are in their innermost or retracted positions wherein their outer ends project to the least extent, if at all, from the exterior of the lamp receptacle 50, 52 and are thereby withdrawn from the retaining holes 72 formed in the side walls of the receptacle units 12, 14- and 16. In this position of the detents 66 the push button cap assembly 18 is free to be withdrawn from the associated panelmounted receptacle unit. This position of the detents is permitted by grooving the plunger to provide a depressed land 70a. This land is formed between an enlargement 70b having a relatively steep wall facing the cam follower elements 66a and an opposing enlargement 700 having a gradually sloping wall 70c facing the cam follower elements 66a. When the plunger 70 is pushed in the direc-' tion to wedge the sloping wall 700 past the followers 66a, the springs 68 yield and the follower elements 66a ride up and over the surface 700 in order to arrive in contact with the cylindrical land surface 70d of materially larger diameter than the land 70a. In so doing, these followers are eased onto the surface 70d by the inclined cam sunface 70c" situated opposite the surface 700'. In this position of the plunger the detents 66 are projected outwardly from the lamp receptacle unit 50, 52 and through the apertures 72 in the side walls of the associated receptacle units 12, .14 or 16. .Thus engaged, the detents hold the assembly 18 in the receptacle unit. The land 70d, of substantially constant diameter, extends over a substantial portion of the length of plunger 70 adequate to accommodate the switch actuation stroke of the plunger 70. As a result, inward movement of the plunger '70 actuates the switch S and in no way disturbs the setting of the detents 66.

However, when itis desired to withdraw the push button assembly 18 from its associated receptacle unit, the finger holds 56b are grasped and the cap 56 is pulled outwardly, and with it 'the plunger 70. Some force is necessary to withdraw the plunger because of friction between the follower tips 66a and the sloping cam surface 700" encountered when the plunger 70 is being moved from its position shown in the right hand portion of FIG- URE 6 to its position shown in FIGURE 8, in order to effect retraction of the detents 66. It will there-fore be evident that the detent mechanism is displacement-sensitive. The displacement referred to is that which must take place between the plunger 74 (and cap 56) and the-base portion of the push button cap assembly 18. It will be noted that this displacement by which the detents 66 are released is in the direction of the return stroke of the plunger.

Return motion of the plunger '70 is effected by a return spring of helical fonm encircling the plunger along a constant-diameter portion of its length,70f, between the enlargement 76b and another enlargement 70g. The spring 1s held captive between these enlargements by first and second stop collars 82 and 84 which, together with the spnng, are free to move independently of each other lengthwise of the plunger 70. Stop'collar 84 is thus movable into and from contact with the enlargement or stop element 70g while stop collar 82 is free to move into and from contact with the enlargement or stop element 701].

Alsothe stop collar 82 is engageable with a shoulder surface or stop abutment 86 formed on the base or inner end of the lamp receptacle structure 50, 52. In like manner the stop collar 84 is movable into and from contact with a stationary stop abutment comprising a step in the interror wall of the guide sleeve 88 in which the stop collar 84 1s slidably received (FIGURE 5). This guide sleeve is fixably retained in an aperture in the base plate 44 and extends outwardly through an aperture in the superimposed spacer plate 42.

With the plunger at rest in the released position as shown at the right in FIGURE 6, the stop collars 82 and 84 are seated against their respective stationary stop abutments 86 and 88, or substantially so, depending upon whether these abutments are effectively more closely spaced in relation to each other than the effective spacing between the respective stop elements 7% and 70g formed on the plunger. In practice these relative spacings are approximately equal and in any case the plunger at rest in the released position is appropriately located in the mecharusm either by the fixed abutments 86 and 88 or by other suitable means.

The plunger enlargement 70g has a steep or abrupt end wall 70g facing and contactable by the stop collar 84 and a gradually sloping opposite end wall 70g". Beyond the enlargement the plunger has a projecting tip portion 76h of substantially constant diameter which projects at a l times through an aperture 30b in the latch plate 30 and through the aligned diamond-shaped variable opening 0 formed between the notched mutually adjacent ends of the lockout plates 26 and 28. With all of the plungers in their released position at rest in the mechanism, the latch control spring 34 presses the latch plate 30 endwise in its guidance groove 32a so as to maintain contact between corresponding sides of the apertures 30b and the adacent corresponding sides of the respective plungers 70 of the different switch operating units. When the plunger is advanced toward the actuated position by pressure on the push button cap 56 the gently sloping cam surface 70g of enlargement 70g cams the latch plate 30 in the direction opposite the pressure of the spring 34 so as to align the associated aperture with the enlargement 70g and permit the latter to pass through the aperture, the aperture being slightly larger than the enlargement. After the enlargement passes the aperture, the latch control spring 34 snaps the latch plate 30 back into its original position and thereby traps the enlargement 70g on the opposite face of the latch plate, such that when manual pressure on the push button cap 56 is removed the return spring 83, attempting to return the plunger, brings the abutment surface 70g into engagement with the inner face of the latch plate 3%. This is the latched position of the plunger, corresponding to the operating position of the associated electrical switch S (or right hand portion of FIGURE 5).

In the process of advancing through the aperture 3% the enlargements leading end 70g wedges its way into the opening between adjacent ends of lockout plates 26 and 23 and forces these plates apart. The length of these plates is such that when they are thus forced apart by arrival of the enlargement 70g into the actuated position of its associated plunger no other plunger can be pressed because the opposite ends of these plates would interfere with movement of the plunger of either or both of the other two switch operating units into their actuated positions at the same time. However, if, with any one switch operating plunger in its actuated position, another plunger is pressed toward its actuated position, the act of advancing its enlargement 70g through the corresponding aperture 30b in the latch plate, temporarily returning the latch plate, trips the latch and thereby releases the previously actuated and latched plunger. Such tripping of the latch by actuation of any switch operating plunger permits abrupt return motion of the released plunger and associated elements under recoil force of the return spring 80 thereof.

In operation, referring to the various operational views, the return spring 80 is under the minimum amount of compression (although appreciable) with the associated switch operating plunger at rest in the released position (or right hand unit in FIGURE 7 and right hand unit in FIGURE 6, for example). It is at its maximum compression with the associated plunger in the switch-actuated position, with the plunger latched by the latch plate 30 (middle unit in FIGURE 7 and right hand unit in FIG- URE It is compressed to an intermediate extent in its maximum shock-absorbing recompressed condition (left hand unit in FIGURE 7, and position shown in FIG- URE 9). Upon and during initiation of the return stroke effected by recoil of spring 80, stop collar 82 picks up and carries plunger stop element 7% and drives the plunger in the direction outward of the supporting panel 10, with the springreacting back against the stop collar 84 seated against the stationary shoulder 83 (FIGURE 5). Be cause of kinetic energy inherent in the momentum of the driven plunger, the plunger could, under the influence of a strong return spring, be driven past the point at which it would release the detents 66 by advancing from the position shown at FIGURE 9 to the position shown in FIGURE 8 relative to the detent cam elements 66a. To avoid this, and to eliminate such excessive displacement of the plunger relative to the detent cam follower elements 66a, the return spring is permitted to recompress and absorb energy from the plunger by the fact that the enlargement 70g now picks up the stop collar 84 and compresses the spring against the stop collar 82 seated on the stationary stop abutment 86 (FIGURE 9).

Absorption of kinetic energy in this manner by the return spring is made possible by the provision of the relatively movable stop collars capturing the return spring between them, and the plunger enlargements 70g and 70b in turn capturing the stop collars between them and cooperating with the stationary abutments in the base structure of the push button cap assembly 18. Compactness derived from this multiple utilization of elements, conveniently organized and arranged within the assembly,

as well as compactness derived from the parallel relationship of the sliding lockout plates and latch plate held captive between guide plates at the base of the receptacle assembly and disposed perpendicularly to the plunger shaft with which they cooperate, makes for a highly compact switch operating mechanism which is narrow in its width dimension measured transversely to the length of the row of integrally associated units. It achieves this result in such manner that rows of units may be mounted in close proximity to each other occupying a minimum span across the width of any instrument panel in which a number of these units are required. In addition, the depth to which the individual units are required to project transversely to the plane of the instrument panel is minimized because of the compact and parallel relationship of the lockout plates and latch plate associated with the individual control plungers.

These and other features and advantages of the invention will be evident from the foregoing description of the presently preferred embodiment, which will be recognized as primarily illustrative and not necessarily delimitative of the scope of the advancements in the art represented thereby.

We claim as our invention:

1. Switch operating mechanism comprising a base having first and second stop abutments in spaced relation thereon, an operating member reciprocatively mounted in relation to said base and having first and second stop elements in spaced relation thereon, a return spring for said operating member, first and second stops carried by said operating member in spaced relation with the return spring held captive between said stops, said stops and return spring being independently movable in relation to said operating member, said first and second stops being engageable with said first and second stop elements and stop abutments, respectively, means in association with said operating member for actuating the same from an initial position in one direction against increasing stress in said return spring reacting between said first stop, picked up by said first stop element, and said second stop engaging said second stop abutment, latch means connected with said base for holding said operating member in actuated position, and means coacting with said latch means for releasing the operating member to permit abrupt return motion thereof toward its initial position impelled by recoil of said return spring, and means absorbing kinetic energy of the operating member on its return motion, including said return spring restrcssed by reaction between the second stop, picked up by the second stop element, and the first stop engaging the first stop abutment.

2. In combination with switch operating mechanism as defined in claim 1, means to support said base, and detent means for holding said base to said support means including cooperating elements releasable by predetermined displacement of the operating member from its initial position in the direction of such return motion.

3. The combination defined in claim 2, wherein the operating member comprises an elongated plunger, the return spring is of helical form slidably encircling the plunger, the first and second stops comprise annular collars slidably encircling the plunger, and the first and second stop elements comprise enlargements on the plunger retaining said collars and spring therebetween.

4. The combination defined in claim 3, wherein the base comprises mutually aligned first and second guideways for the plunger and stop elements, the first guideway having a shoulder thereon engageable by the first stop, and the second guideway having a shoulder thereon engageable by the second stop.

5. Push-button type switch operating mechanism comprising a base having first and second stop abutments in spaced relation thereon, a plunger reciprocatively mounted in relation to said base and having first and second stop elements in spaced relation thereon, a plunger return spring encircling said plunger, first and second stop collars carried by said plunger in spaced relation with the return spring held captive therebetween, said collars and return spring being independently movable in relation to said plunger, said first and second stop collars being engageable with said first and second stop elements and stop abutments, respectively, push button means connected with said plunger for actuating the same from an initial position in one direction against increasing stress in said return spring reacting between said first stop collar, picked up by said first stop element, and said second stop collar engaging said second stop abutment, holding means connected with said base for holding said plunger in actuated position, and means coacting with said holding means for releasing the plunger to permit return motion thereof abruptly toward its initial position impelled by recoil of said return spring, and means absorbing kinetic energy of the plunger on its return motion, including said return spring restressed by reaction between the second stop collar, picked up by the second stop element, and the first stop collar engaging the first stop abutment.

6. A multi-unit push-button type switch system comprising a common support for a plurality of switches, a plurality of switch-operating mechanisms removably mounted in transversely aligned generally parallel relationship therein, each such mechanism comprising a base removably connected with said support and having first and second stop abutments in spaced relation thereon,

a plunger reciprocatively mounted in relation to said base and having first and second stop elements in spaced relation thereon, a plunger return spring encircling said plunger, first and second stop -collars carried by said plunger in spaced relation with the'return spring held captive therebetween, said collars and return spring being independently movable in relation to said plunger, said first and second stop collars being engageable with said firstand second stop elements and stop abutments, respectively, push button means connected with said plunger for actuating the same from an initial position in one direction against increasing stress in said return spring react ing between said first stop collar, picked up by said first stop element, and said second stop collar engaging said second stop abutment, latch means on said support for holding said plunger in actuated position, and means coacting with said latch means for releasing the plunger to permit return motion thereof abruptly toward its initial position impelled by rec'oil of said return spring, and means absorbing kinetic energy of the plunger on its return motion, including said return spring restressed by reaction between the second stop collar, picked up by the second stop element, and the first stop collar engaging the first stop abutment, the latch means comprising means common to the plungers and actuatable to its released position to release any latched plunger by actuation movement of any other plunger.

7. The multi-unit system defined in claim 6, wherein the common latch means comprises a plate member reciprocatively mounted in the support in a general plane substantially perpendicular to the plungers, a latch con trol spring reacting against said plate member in one direction toward latching position, said plate member and plungers having cooperating camming surfaces thereon whereby actuation of any plunger shifts the plate member oppositely to latch-released position against the return force of the latch control spring, each plunger having a latch abutment thereon engageable with the plate member in its returned position to hold the plunger thereby against return.

8. The system defined in claim 7, wherein the plunger has an enlargement thereon having a sloping leading end comprising'the latch camming element thereof and having a relatively abrupt lagging end comprising the latch abutment.

9. The system defined in claim 8, wherein the plate member has a separate opening therein for each plunger,

of a size and location permitting passage of the plunger enlargement through the opening during actuation and return of the plunger.

10. The system defined in claim 9, and lockout means comprising, between each two successively adjacent plungers, a separate lockout plate reciprocatively mounted in the support in proximate parallel sliding relation to the latch plate, said plungers and the respectively adjacent ends of the lockout plate having cooperating lockout camming elements mutually engageable by actuation of either plunger to shift the lockout plate thereby into obstructive relation to the other plunger, preventing conjoint actuation of the two plungers.

11. The system defined in claim 10, wherein the plungers lockout camming element comprises the leading end of its enlargement, and the lockout plate is stationed beyond the latch plate to be engaged by such leading end upon completion of plunger actuation.

12. Switching mechanism comprising a base, a plunger reciprocable in the base between actuated and return positions, resilient means carried by and reacting on the plunger from the base in the actuated position of the plunger, urging the plunger toward its return position, means on the base cooperating with the plunger to detain the plunger in its actuated position and operable to release the plunger for return movement, and means to absorb kinetic energy of the plungers return impelled by said resilient means, said absorption means including said resilient means, a stop abutment on the base, and a stop member on the plunger picking up the resilient means and thereby restressing the resilient means by reaction thereof against said stop abutment on the return stroke of said plunger. 1

13. Switching mechanism comprising a base, a springreturned plunger reciprocable in the base through a range including actuated position, an opposite detent deactuating position and an intermediate return position, a support for the base, detent means including cooperating elements on the base and the support operable for holding the base to the support and operable by movement of the plunger in the base between detent deactuating position and return position to deactuate and actuate the detent means, latch means mounted on the support to be actuated by movement of the plunger to its actuated position for engaging and holding the plunger in such position, means for releasing the latch means to permit springreturn movement of the plunger, and shock-absorption means engageable by the plunger on its return motion and reacting against said base, thereby preventing overtravel of the plunger to the detent deactuating position.

References Cited by the Examiner UNITED STATES PATENTS 2,639,337 5/1953 Framhein 200-5 2,740,004 3/1956 Baldasare 200-5 FOREIGN PATENTS 1,299,124 2/1962 France.

KATHLEEN H. CLAFFY, Primary Examiner.

M. GINSBURG, Assistant Examiner. 

12. SWITCHING MECHANISM COMPRISING A BASE, A PLUNGER RECIPROCABLE IN THE BASE BETWEEN ACTUATED AND RETURN POSITIONS, RESILIENT MEANS CARRIED BY SAID REACTING ON THE PLUNGER FROM THE BASE IN THE ACTUATED POSITION OF THE PLUNGER, URGING THE PLUNGER TOWARD ITS RETURN POSITION, MEANS ON THE BASE COOPERATING WITH THE PLUNGER TO DETAIN THE PLUNGER IN ITS ACTUATED POSITION AND OPERABLE TO RELEASE THE PLUNGER FOR RETURN MOVEMENT, AND MEANS TO ABSORB KINETIC ENERGY OF THE PLUNGER''S RETURN IMPELLED BY 